FRIDAY, March 30 (HealthDay News) -- The declining number of U.S. medical students who choose psychiatry as a specialty is cause for concern because there's already a shortage of psychiatrists, experts warn.

The overall downward trend has occurred for the past six years, according to a National Resident Matching Program report.

Medical schools need to provide more information and training to medical school students so they know psychiatry can be a profitable and rewarding career, the American Psychiatric Association (APA) said.

"In 2010, there was a slight increase in the number of seniors choosing psychiatry, but overall the trend has been downward," APA president Dr. John Oldham said in an association news release.

"We need to reach out to medical students in more effective ways than simply exposing them to a four-week clerkship on an inpatient unit, with no follow-up of the patients they have cared for," Oldham said. "Establishing and maintaining ongoing relationships with patients is one of the key factors that makes psychiatry such a fulfilling career."

The reasons for the decline in students choosing to pursue a career in psychiatry aren't well known, but there could be several factors, said Dr. James Scully Jr., the APA's medical director and CEO.

"This is a very exciting time for psychiatry, when we have more scientific developments in the field than ever before, but this means that the field is evolving in ways in which the outcome is unknown," Scully said in the news release. "It's a great time for young doctors to have an impact on what the future of psychiatry will look like."

There are about 50,000 psychiatrists in the United States -- too few to serve all the patients who need help, especially in rural areas, according to the APA. The group also noted that about half of currently practicing psychiatrists are over the age of 55, and many will soon retire.